Avatar, a 2009 epic sci-fi flick written and directed by James Cameron, has marked a major technological breakthrough and ushered in a new era in digital effects. Although development on the movie began in 1994, when Cameron wrote an 80-page scriptment for the film, the director soon found he would have to wait for the necessary technology to become available if he were to achieve his vision of the film.

Beginning Dec. 20, a special edition of Avatar is landing on Apple’s iTunes Store packing in interesting iTunes Extras unavailable on other platforms. According to the press release, these interactive digital enhancements let fans:

Deconstruct some of the movie’s most memorable scenes to reveal how James Cameron applied special effects to create the breathtaking world of Pandora. This new feature will also enable consumers to interact with the performance capture and visual effects levels in 17 of the film’s scenes. For the first time ever, Green Screen X-ray gives users an interactive look through the visual effects levels to see the original green screen footage behind a pivotal scene.

Other perks include an original screenplay by James Cameron, Cameron’s scriptment (a novella with some scenes broken out into dialogue), a gallery of 1,700 images and more. You can pre-order your digital copy of this highest-grossing movie of all time (Blu-ray best-seller, too) at www.iTunes.com/Avatar beginning today. The flick costs $15 in standard-definition (add a $5 premium to enjoy it in 720p high-definition).